1. Field of the Invention
The present invention relates to part of the body structure of a vehicle and, more particularly, to the front body structure of a car body which suppresses deformation of a cabin of a car body during a collision and which dissipates and relieves impacts or shocks on the car body during the collision.
Typically, the front body portion of a vehicle is provided with a suspension cross member extending at the rear end portion of an engine compartment or room between a pair of front frames generally placed on opposite sides of the engine room. A power train, formed by the engine, a transmission, a differential, etc., is disposed forward of the vehicle body, relative to the suspension cross member, in the engine room.
2. Description of Related Art
Considering the vehicle to be subjected to a straight-on, front-end collision, if an impact on the vehicle is slight, the energy delivered to the front body structure is absorbed by a collapse of what is called a "crash space", which includes spacial volumes formed, e.g., between the front portion of the engine room and the power train, between the power train and the suspension cross member, and between the suspension cross member and a dash panel. However, if the impact is sufficiently high, the engine room will collapse too much for the crash space to absorb the impact. That is, the power train will collide with the suspension cross member, located rearward of the vehicle relative to the power train, due to the collapse of the engine room. Furthermore, the suspension cross member typically interferes with the dash panel separating the engine room from the cabin so as to thrust the dash panel in the rearward direction toward the cabin of the car body. This results in deformation of the cabin.
For suppressing the deformation of the cabin so that it is as small as possible in order to assure the safety of the occupants of the cabin, it is clear that the crash space in the engine compartment should be made as large as possible. However, there are limits to the permissible dimensions of the crash space, because enlarging the crash space in the engine room necessitates a decrease in cabin space.
A structure suitable for enlarging the crash space in the engine room, requiring no decrease in cabin space, is known from, for instance, Japanese Utility Model Publication No. 61-7963. The front body described in this publication is structured such that when the power train is forced rearward, due to a front-end collision, and collides with the suspension member, the suspension member and a part mounting the suspension member are ruptured or broken. In this known front body structure, the suspension member is designed to collapse or crush sufficiently to eliminate the need to decrease cabin space.
However, in such a front body structure, which allows the suspension member itself to collapse during a collision of the vehicle, the action of shocks caused by the collapse of the suspension member during a collision of the vehicle causes a dynamic weight transfer in the cabin. Injuries to cabin occupants, therefore, may occur.